Aftermarket dual-fuel injection systems using a variety of different fumigants have been proposed as alternatives to expensive after-treatment to control NOX emissions from legacy diesel engines. However, our previous work has shown that available add-on systems using hydrous ethanol as the fumigant achieve only minor benefits in emissions without recalibration of the diesel fuel injection strategy. This study experimentally re-evaluates a novel aftermarket dual-fuel port fuel injection (PFI) system used in our previous work, with the addition of higher flow injectors to increase the fumigant energy fraction (FEF), defined as the ratio of energy provided by the hydrous ethanol on a lower heating value (LHV) basis to overall fuel energy. Results of this study confirm our earlier findings that as FEF increases, NO emissions decrease, while NO2 and unburned ethanol emissions increase, leading to no change in overall NOX. Peak cylinder pressure and apparent rates of heat release are not strongly dependent on FEF, indicating that in-cylinder NO formation rates by the Zel’dovich mechanism remains the same. Through single zone modeling, we show the feasibility of in-cylinder NO conversion to NO2 aided by unburned ethanol. The modeling results indicate that NO to NO2 conversion occurs during the early expansion stroke where bulk gases have temperature in the range of 1150–1250 K. This work conclusively proves that aftermarket dual fuel systems for fixed calibration diesel engines cannot reduce NOX emissions without lowering peak temperature during diffusive combustion responsible for forming NO in the first place.
Aftermarket dual-fuel injection systems in diesel engines using hydrous ethanol have been developed as a means to lower emissions from older diesel-powered equipment. However, our previous work has shown that the emissions benefits of currently available aftermarket intake fumigation injection systems can be inconsistent with manufacturer claims. Our current study evaluates a newly developed aftermarket dual fuel system that incorporates a novel fuel heating system and port fuel injection (PFI). This paper describes an experimental investigation of engine-out emissions from a John Deere 4045HF475 Tier 2 engine with port injection of 180 proof (90% ethanol by volume) hydrous ethanol. The engine was retrofitted with a custom fuel heat exchanger to heat the hydrous ethanol to a range of 46–79°C for helping to improve fuel vaporization in the intake port. PFI duration was controlled using engine speed and throttle position as inputs to achieve a desired fumigant energy fraction (FEF), defined as the amount of energy provided by the hydrous ethanol based on lower heating value (LHV) over the total fuel energy provided to the engine. Data was collected over a range of FEF with direct injected diesel for eight operating modes comparing heated versus unheated hydrous ethanol. Results of the study indicate that as FEF increases, NO emissions decrease, while NO2, CO, THC, and ethanol emissions increase. In addition, it was found that preheating the ethanol using engine coolant prior to injection has little benefit on engine-out emissions. The work shows that the implemented aftermarket dual-fuel PFI system can achieve FEF rates up to 37% at low engine load while yielding modest benefits in emissions.
Aftermarket dual-fuel injection systems using a variety of different fumigants have been proposed as alternatives to expensive after-treatment to control NOx emissions from legacy diesel engines. However, our previous work has shown that available add-on systems using hydrous ethanol as the fumigant achieve only minor benefits in emissions without recalibration of the diesel fuel injection strategy. This study experimentally re-evaluates a novel aftermarket dual-fuel port fuel injection (PFI) system used in our previous work, with the addition of higher flow injectors to increase the fumigant energy fraction (FEF), defined as the ratio of energy provided by the hydrous ethanol on a lower heating value (LHV) basis to overall fuel energy. Results of this study confirm our earlier findings that as FEF increases, NO emissions decrease, while NO2 and unburned ethanol emissions increase, leading to no change in overall NOx. Peak cylinder pressure and apparent rates of heat release are not strongly dependent on FEF, indicating that in-cylinder NO formation rates by the Zel'dovich mechanism remain the same. Through single zone modeling, we show the feasibility of in-cylinder NO conversion to NO2 aided by unburned ethanol. The modeling results indicate that NO to NO2 conversion occurs during the early expansion stroke where bulk gases have temperature in the range of 1150–1250 K. This work conclusively proves that aftermarket dual fuel systems for fixed calibration diesel engines cannot reduce NOx emissions without lowering peak temperature during diffusive combustion responsible for forming NO in the first place.
Aftermarket dual-fuel injection systems in diesel engines using hydrous ethanol as secondary fuel have been developed as a means to lower emissions from older diesel-powered equipment. However, our previous work has shown that the emissions benefits of currently available aftermarket intake fumigation injection systems can be inconsistent with manufacturer claims. Our current study evaluates a newly developed aftermarket dual-fuel system that incorporates a fuel heating system and port fuel injection (PFI). This paper describes an experimental investigation of engine-out emissions from a John Deere 4045HF475 Tier 2 engine with port injection of 180 proof (90% ethanol by volume) hydrous ethanol. The engine was retrofitted with a custom fuel heat exchanger to heat the hydrous ethanol to a range of 46–79 °C for helping to improve fuel vaporization in the intake port. PFI duration was controlled using engine speed and throttle position as inputs to achieve a desired fumigant energy fraction (FEF), defined as the amount of energy provided by the hydrous ethanol based on lower heating value (LHV) over the total fuel energy provided to the engine. Data was collected over a range of FEF with direct injected diesel for eight operating modes comparing heated versus unheated hydrous ethanol. Results of the study indicate that as FEF increases, NO emissions decrease, while NO2, CO, THC, and unburned ethanol emissions increase. In addition, it was found that preheating the ethanol using engine coolant prior to injection has little benefit on engine-out emissions. The work shows that the implemented aftermarket dual-fuel PFI system can achieve FEF rates up to 37% at low engine load while yielding modest benefits in emissions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.